tools/wltests: better check for device being online
tools/wltests: better check for device being online

Adb can report a device as being 'offline', let's refine the devices
report for the expected 'device' string when they are actually available.
Use the same cure for fastboot.

Signed-off-by: Patrick Bellasi <431c86f368affbc3148c4669fbd465131f7e82cb@arm.com>

credp/lisa,credp/lisa,ARM-software/lisa,bjackman/lisa,credp/lisa,bjackman/lisa,ARM-software/lisa,ARM-software/lisa,ARM-software/lisa,credp/lisa